I am thinking about purchasing an I/O magic burner. What is the difference between 8x and 4x-what are the advantages/disadvantages to each? Also which speed media would work best with either? Roxio software is included with the burner but from what I have read, it is better to us DVD shrink and decrypter.Why should the Roxio not be used? I am just learning the basics and reading through the guides,but want to make sure I understand everything so I can explain it to my husband. Thanks so much!